Authorities say the equivalent of 2,000 Olympic swimming pools of mining waste has been discharged into waterways in British Columbia's Cariboo region, forcing hundreds to stop using water in the area.
The tailings pond of the Mount Polley mine, about 140 kilometres southeast of Quesnel in northern B.C., was breached early Monday, forcing a water-use ban.
The Cariboo Regional District issued the advisory for the town of Likely and for residents around Quesnel Lake, Polley Lake, Hazeltine Creek and Cariboo Creek.
The initial water-use ban affected about 300 people, but that number was likely to grow since the advisory was expanded to include residents along the nearby Quesnel and Cariboo Rivers.
The Quesnel River is linked to the Fraser River, one of B.C.'s main arteries, but authorities have not imposed a water-use ban on communities by the Fraser, saying it is unclear if contaminants have gone that far.
The Ministry of Environment of B.C. says the extent of the environmental damage is not yet clear and water in the area will be tested in the coming days.
The Cariboo Regional District has posted a video on YouTube showing the breach and a river completely covered in what appears to be light grey mining waste.
District chairman Al Richmond said search and rescue crews evacuated some campers in the Mount Polley area. But shelters were not provided for them, as they appear to have set up camp elsewhere.
Richmond says most of the waste appears to be contained in Hazeltine Creek, though some of the material flowed into Quesnel Lake and Polley Lake.
Mount Polley is an open pit copper and gold mine owned by the Imperial Metals Corporation (TSX:III). The company has been involved on the construction or operation of seven mines, the majority in British Columbia.
Requests for comment from Imperial were not immediately returned.
Tailings ponds are often large bodies of water containing waste water from mines, and have been known to contain poisonous materials such as arsenic and mercury.